1. Field of the Invention
This invention relates to an IC card including a circuit board on which parts are mounted and to a method of manufacturing the IC card.
2. Description of the Related Art
FIG. 10 is an exploded view which illustrates a method of assembling a conventional IC card. A main frame 1 comprises a U-shaped frame portion 1a for forming a frame of the card together with a connector 4 to be described later and board supporting portions 1b and 1d, each of which is integrally formed with the frame portion 1a. The board supporting portion 1b has a projecting portion 1c formed at the central portion thereof. A circuit board 2 has circuit patterns (omitted from illustration) or both sides thereof. An IC package 3, which is a function part, is mounted on the circuit board 2 so that an electrical connection is established between them. A connector 4 is connected to either side of the circuit board 2, while a board fixing hole 2a is formed in the central portion of the circuit board to receive the projecting portion 1c of the board supporting portion 1b. The connector 4 constitutes a portion of the frame of the card, the connector 4 being electrically connected to external equipment (omitted from illustration) to which the IC package 3 and the IC card are connected. A surface panel 8a and a reverse panel 8b are protection panels made of metal plates or the like. A sub-frame 6 is disposed between the surface panel 8a and the circuit board 2 as a spacer. Since FIG. 10 is a schematic view which illustrates the IC card, some portions are omitted or schematically illustrated.
The structure of a conventional IC card is illustrated further in detail in FIGS. 11A and 11B. FIG. 11A is a plan view which illustrates the structure of the main frame 1. FIG. 11B is a cross sectional view taken along line XIB--XIB of FIG. 11A. Referring to FIGS. 11A and 11B, reference numeral 1d represents a board supporting portion formed at a position opposing the connector 4 of the frame portion 1a, the board supporting portion 1d being formed integrally with the frame portion 1a similarly to the board supporting portion 1b. Reference numerals 7a and 7b represent connector leads for establishing electrical and mechanical connection between the connector 4 and the circuit board 2.
A conventional method of assembling the IC card will now be described. First, the IC packages 3 are connected to both of the surfaces of the circuit board 2 by soldering so that the IC packages 3 are mounted. Then, the connector 4 is electrically and mechanically connected to the circuit board 2 by soldering the connector leads 7a and 7b to both surfaces of either side of the circuit board 2 (see FIG. 11B). A structure constituted by combining the circuit board 2 and the connector 4 is called a "module". Then, the module is so fastened to the main frame 1 that the connector 4 constitutes one of the sides of the frame of the card. At this time, the projecting portion 1c formed on the board supporting portion 1b is inserted into the board fixing hole 2a formed in the central portion of the circuit board 2, followed by deforming of the leading portion of the projecting portion 1c.
Then, the sub-frame 6 is secured to the upper surface of the circuit board 2 by an adhesive agent (omitted from illustration). The sub-frame 6 is secured at the position at which the board supporting portion 1d of the circuit board 2 is located so that the circuit board 2 is interposed between the sub-frame 6 and the board supporting portion 1d. The height of the sub-frame 6 is the same as the distance from the circuit board 2 to the surface panel 8a. Finally, the surface panel 8a and the reverse panel 8b are bonded to the frame portion 1a of the main frame 1, the connector 4 and the sub-frame 6 from their two sides with a sheet adhesive agent (omitted from illustration). As a result, the module composed of the circuit board 2 and the connector 4 is secured to the main frame 1. Further, the surface panel 8a and the reverse panel 8b are supported by the frame portion 1a of the main frame 1, the connector 4 and the sub-frame 6. Therefore, desired mechanical strength can be satisfied.
The conventional IC card has suffered from the problem that the number of IC packages that can be mounted has been unsatisfactorily limited because only one circuit board can be mounted if the IC card is intended to have desired mechanical strength.